The present invention relates to pipe couplings in general, and more particularly to improvements in flexible pipe couplings which employ sleeves of elastomeric material. Still more particularly, the invention relates to improvements in pipe couplings of the type wherein the sleeve is surrounded by the split ring of a clamp and the diameter of the split ring can be reduced to thereby urge the internal surface of the sleeve into sealing engagement with the external surfaces of the pipes.
It is already known to provide the sleeve of the above outlined pipe coupling with an internal partition in the form of a collar extending from the internal surface of the sleeve and abutting against the end faces of the pipes whose end portions are inserted into the respective open ends of the sleeve. Reference may be had to Swiss Pat. No. 432,956. It is also known to provide such a sleeve with internal grooves which flank the partition and whose volume is reduced in response to radial compression of the sleeve under the action of the split ring. It is further known to provide the split ring with a circumferentially extending corrugation which is received in the circumferentially extending groove in the external surface of the sleeve. Reference may be had to German Utility Model No. 73 16 306 which further discloses that the marginal portions (i.e., the axial end portions) of the split ring can be bent inwardly into planes which are normal to the axis of the sleeve. The gap between the lugs which are provided at the ends of the split ring and through which the bolts and nuts of the tensioning device of the clamp extend exposes a portion of the material of the elastic sleeve. This is undesirable because, when the lugs are caused to move nearer to each other, some material of the sleeve bulges outwardly and penetrates into the gap so that the latter cannot be completely closed, i.e., the sleeve imposes limits upon the extent of its radial compression by the clamp. In many instances, the extent of penetration of the material of the sleeve into the gap is so pronounced that the maximum achievable radial compression of the sleeve does not suffice to ensure the establishment of a reliable sealing action between the internal surface of the sleeve and the external surfaces of the inserted end portions of the pipes. Moreover, the sleeve is likely to be damaged because some of its material is pinched between the lugs of the split ring. Still further, the sealing action between the sleeve and the pipes in the region between the lugs of the split ring is much less pronounced than in the other regions so that the fluid medium which is confined in the pipes is likely to escape if its pressure exceeds the pressure in the surrounding area.